Misdiagnosis causes over-correction. This workflow starts with pattern checks, then applies grind, ratio, and temperature moves in a strict order.
Sour pattern checks and corrections
If taste is sharp, thin, and salty while time is 24 seconds or faster, treat it as under-extraction and grind finer first.
If time is already in 25 to 35 seconds and sourness remains, extend yield by 1 to 2g before touching temperature.
Bitter pattern checks and corrections
If taste is dry, ashy, and hollow while time is 36 seconds or slower, grind coarser first and keep dose fixed.
If time is in band but bitterness remains, shorten yield by 1 to 2g. For dark roasts, lower temperature by 1C only after ratio check.
Mixed sour plus bitter means test evenness first
When sour and bitter show up together, pause recipe changes and check for uneven extraction signs: spraying, uneven flow, or large shot-time spread.
Correct prep consistency first, then rerun one controlled shot before deciding whether grind or ratio should move next.